Question

In a $△ABC$, $BC=AB$ and $\angle B={80}^0$. Then $\angle A$ is equal to?

• A. ${80}^0$
• B. ${40}^0$
• C. ${50}^0$
• D. ${100}^0$

Answer 1

Answer: (C)

${50}^0$

Given: $BC=AB$, $\angle B={80}^{\circ }$
Since, $BC=AB$
$\angle A=\angle C=x$ (Angles opposite to equal sides are equal)
Sum of angles of a triangle = 180
$\angle A+\angle B+\angle C=180$
$x+80+x=180$
$2x=100$
$x={50}^{\circ }$
Thus, $\angle A={50}^{\circ }$